1. Field of Invention
The technical scope of the invention is that of devices to manage the thermal energy on a vehicle and more particularly on a vehicle incorporating an electric generator associating a fuel cell and a hydrogen reformer.
2. Description of the Related Art
Fuel cells convert the chemical energy of an oxido-reducing reaction implementing hydrogen into electrical energy. These fuel cells are increasingly important in vehicles both as an auxiliary power chamber and as main energy generating means.
In fact, they enable the carbon dioxide gaseous emissions from the vehicle to be strongly reduced. The cells practically release only water vapor which can be recovered.
Fuel cells are well known to the Expert. Proton exchange membrane fuel cells (PEMFC) are known whose main characteristic is that of being able to function at low temperatures (of around 80° C.).
These may be associated with a hydrogen reformer which enables hydrogen to be generated by using water and a fuel such as petrol, diesel oil, methanol, natural gas, diester or other hydrocarbon.
The reformer operates at a generally high temperature (from 800° C. to 1000° C.) whereas the membrane fuel cell functions optimally at a temperature of around 80° C.
The use of thermal energy generated by a fuel cell has been proposed to warm the interior of the vehicle or else to air condition it by coupling the cell with a conventional cooling circuit implementing a compressor.
Patent FR-2805926 thus proposes a thermal management device for a vehicle in which a primary circuit of heat conducting fluid ensures the temperature regulations of the fuel cell. This primary circuit is in a thermal exchange relation with a secondary cooling circuit.
The drawbacks to known devices lie in that the thermal energy available from the fuel cell is not enough to ensure most of the necessary thermal functions in a vehicle. Moreover, it is necessary for the cooling circuit temperature of the fuel cell to be regulated at around 80° C. thereby limiting the possibility of employing thermal energy in the exchange circuits.
The cooling circuit thus incorporates a compressor, and if this enables the primary circuit temperature to be partly reduced, it is essentially electrical energy which is supplied to the compressor enabling the desired cooling level to be obtained. This results in additional stressing of the fuel cell.
Furthermore, cooling compressors are noisy appliances whose implementation in a vehicle may cause problems, namely when the vehicle is a military vehicle which must stay in a surveillance position whilst remaining as stealthy as possible, both from an acoustic and thermal perspective.